This is the transfection protocol used at the LBTC lab for CHO DG44 cells. The transfection reagent is PEI ([http://en.wikipedia.org/wiki/Polyethylenimine polyethylenimine]).

Please use the provided Excel sheet to calculate the volume of plasmid you should add to the cells. Replace every value in red by your own, then print the sheet out and follow the provided protocol.

1. Passage seed 1 day prior to transfection.

2. Prepare tubes (yellow caps with holes) by addition of the calculated amount of DNA.

3. Centrifuge the necessary volume of seed (after a PCV measurement), remove conditioned medium with the pump (use a 2 ml serological pipet with a broken neck) and resuspend (first in 10 ml) in necessary volume of fresh medium to achieve the required cell density (3 mio/ml).

4. Add 5 mL of the cell suspension to the tube with DNA and mix orbitally.

5. Add the PEI (45 µl) to the Cell+DNA mixture as soon as possible, flick 3 times.

6. Place in the incubator at 37°C.